1. Field of the Invention
The present invention relates to a stiffened panel structure for use in bridges, load bearing floors, large haulage containers, dump trucks or other structures where panel stiffening is advantageous.
A panel that must support weight is heavy due to its own thickness and inherent weight. A more efficient means of achieving the load support and yet provide the requisite panel strength, is to utilize a thinner panel with a reinforcing substructure. In this manner a thinner, lighter weight panel may be obtained, that will yet provide the rigidity and strength required. One of the methods of providing a reinforcing substructure is to attach a series of cross-aligned beams to the panel.
One set of support beams aligned parallel to each other are referred to as stiffening ribs. Another set of support beams aligned parallel to each other but generally perpendicular to the stiffening ribs are referred to as transverse beams.
The stiffening ribs may be of differing cross-sectional shapes but are most generally a formed channel. The stiffening ribs are then welded to the panel. Transverse beams may also be of varying cross-sectional shapes but are generally a fabricated channel. The transverse beams are generally deeper in cross-section than the stiffening ribs and thus include cut-outs that allow them to fit over the stiffening ribs. The transverse beams are then welded onto the panel and the stiffening ribs.
The interaction between the deformation of the stiffening ribs and the transverse beams results in abnormally high stresses and a susceptibility to fatigue of the structure, particularly at the point on the transverse beam where the stiffening ribs are welded to the transverse beams. Load stresses have caused cracks to appear in the transverse beam and propagate across the section of the transverse beam resulting in shorter service life, reduced load bearing capacity or both.
It is therefore an object of the present invention to provide an improved cross-stiffened panel structure. The resulting structure would have a longer fatigue life or could be fabricated from thinner material with a more efficient structure obtained.